Engineering the interfacial doping of 2D heterostructures with good bidirectional reaction kinetics for durably reversible sodium-ion batteries

Interfacial doping engineering has been considered a promising strategy to improve the reaction kinetics of 2D heterostructures in sodium-ion batteries (SIBs). Much attention has been paid to the enhancement mechanism of reaction kinetics of pristine heterostructures during discharge, whereas less attention has been given to the optimization of reaction kinetics of discharged products during charge. Therefore, there is an urgent need for systematic understanding and design guide for interfacial doping engineering of 2D heterostructures to achieve good bidirectional reaction kinetics. In this paper, interfacial doping engineering is designed by the guidance of theoretical calculation, a new interface composed of Co-doped MoS2 (Co-MoS2) and N-doped graphene (NG) has excellent electrical conductivity and Na+ adsorption ability during discharge. Moreover, the revealed Na2S-Mo(Co)/NG interface is greatly beneficial to the dispersion, adsorption, and decomposition of Na2S and the overall electrical conductivity during charge. The good bidirectional reaction kinetics of Co-MoS2/NG interfaces in cobalt-doped MoS2 anchored on three-dimensional nitrogen-doped carbon (Co-MoS2/3DNC) composites have been systematically demonstrated by electrochemical characterization technologies. Therefore, an efficient reversible conversion reaction is enabled by the Co-MoS2/NG interfaces. The Co-MoS2/3DNC shows good rate performance and excellent long-term cycling stability of 1500 cycles at the current density of 1 A g−1. This work provides new insight into designing interfacial doping engineering for highly reversible and durable conversion-type composite anodes.